1. Field
The present disclosure relates to electronic devices—e.g., notebook computers and like electronic devices furnished with CPUs (central processing units)—having encased heat-emitting components that emit heat during operation, and in particular relates to the structure of heat-dissipating units that exteriorly release heat from heat-emitting components.
2. Description of the Related Art
Improving the performance of, for example, notebook computers—which are one instance of electronic devices—entails increase in the amount of heat emitted from the heat-emitting components such as the CPU. Further, a notebook computer is a portable electronic device, and to reduce its size and weight as a portable electronic device, the various electronic components are packed into the narrow inside of its casing. Therefore, the provision of heat-dissipating units that offer high performance by effectively releasing to the casing exterior the heat emitted from the heat-emitting components is being called for.
In order to respond to such needs, in an electronic device, a heat-dissipating unit is used which includes: a heat-dissipating component having heat-dissipating fins to which heat transfers from the heat-emitting components; and a fan acting as an air blower for supplying cooling air to the heat-dissipating component. In a conventional heat-dissipating unit of this sort, the CPU as a heat-emitting component is caused to contact directly with the heat-dissipating component, or contact indirectly with the heat-dissipating component via a heat pipe or the like, in order to transfer the heat emitted from the CPU to the heat-dissipating component, so that the heat transferred from the heat-emitting component is released to the casing exterior by the cooling air supplied from the fan. In a conventional heat-dissipating unit of this sort, it is effective to increase the surface area of the fins in order to enhance the heat-dissipating effect, and a plurality of fins are formed and disposed parallel to each other, in a narrow, limited space at short intervals. However, when the intervals at which the fins disposed parallel to each other are formed are short, fine dust contained in the cooling air supplied from the fan is likely to adhere to, for example, the end surfaces of the fins along the side nearer the fan. Once dust adheres to the fin end surfaces, dust is likely to accumulate rapidly. Gaps among the fins tend to become filled with the accumulated dust, and the accumulated dust tends to cover the entire surface of the heat-dissipating component on the side where the cooling air supplied from the fan flows into the heat-dissipating component. When dust accumulates, the fan cannot supply cooling air into the gaps among the fins, and consequently the cooling effect of the heat-dissipating unit deteriorates significantly.
In order to prevent the above-described adhesion of dust to fin end surfaces from deteriorating the cooling effect of a heat-dissipating unit, Japanese Laid-Open Patent Publication No. 2009-163623 suggests a heat-dissipating unit that includes a cleaning component for removing dust adhering to fin end surfaces along the side nearer the fan.
FIG. 10 illustrates an outline of the structure of a conventional heat-dissipating unit for use in electronic devices as described in Japanese Laid-Open Patent Publication No. 2009-163623.
The conventional heat-dissipating unit 100 includes a fan 101 for supplying cooling air, and a heat-dissipating component (heat sink) 104 having fins 104b. Cooling air supplied from the fan 101 is released through gaps among the fins 104b to the exterior of a casing 105, thereby releasing, to the exterior of the casing 105, heat that is generated in a CPU (not shown) that is a heat-emitting component, and which is transferred to the heat-dissipating component 104.
A workable component 102 of a cleaning member for scraping off dust adhering to the end surfaces of the fins 104 along the side nearer the fan 101, and a moving mechanism 103 for moving the workable component 102, are disposed between the heat-dissipating component 104 and the fan 101.
As shown in FIG. 11, the conventional heat-dissipating unit 100 includes a locking plate 107 for locking a piston 106 connected to the workable component 102. By working the locking plate 107, the workable component 102 cleans the end surfaces of the fins 104b. Specifically, as shown in FIG. 11(a), the workable component 102 is usually fixed, by the locking plate 107, so as to be depressed by the piston 106. As shown in FIG. 11(b), the piston 106 is unlocked by a user working the locking plate 107. When the piston 106 is unlocked, the workable component 102 is shifted upward to the upper-end part of the fins by the urging force of a spring component 108 provided in the moving mechanism 103, with the workable component 102 scrubbing the end surfaces of the fins 104b, thereby removing dust adhering to the end surfaces of the fins 104b. The removed dust is discharged outside the casing 105 by cooling air supplied from the fan 101.
Japanese Laid-Open Patent Publication No. 2009-163623 also discloses a method in which a thermally deformable component is connected to, as a moving mechanism for, the workable component 102, and the thermally deformable component is deformed by heat emitted due to operation of the heat-emitting-component, CPU, to remove dust on the end surfaces of the fins 104b. 
In the conventional heat-dissipating unit 100 of the electronic device, the workable component 102 of the cleaning member contacts with the end surfaces of the fins 104b to which dust contained in cooling air supplied from the fan 101 adheres, to allow the dust adhering thereto to be wiped off. The workable component 102 removes a great amount of dust accumulated on the end surfaces of the fins 104b along the side nearer the fan 101. Therefore, flow of cooling air into the heat-dissipating component 104 is not prevented.
However, in the conventional heat-dissipating unit 100, in order to allow the workable component 102 to remove dust, a mechanism for moving the workable component 102 upward and downward along the end surfaces of the fins 104b is to be provided, and the operation for moving the workable component 102 is to be performed by a user. On the other hand, in a case where heat emitted in the heat-emitting components is detected, and cleaning is performed by using the thermally deformable component without causing a user to perform the operation, the workable component 102 cannot be moved for cleaning at a temperature lower than a temperature at which the deformation occurs. Further, due to limitations on the extent to which the thermally deformable component is deformable, the mechanism for moving the workable component 102 is inevitably to be larger-scale.